This invention relates to a corrosion resistant apparatus for processing substrates, and in particular, for processing semiconductor wafers.
In many types of manufacturing processes, substrates are processed in process chambers containing corrosive process environments. For example, in semiconductor fabrication processes, corrosive process gases are used to deposit material upon, etch, or clean semiconductor wafers. Semiconductor processes are typically carried out in an enclosed process chamber containing metallic, ceramic, glass and polymer components. Metal components are fabricated from metal alloys such as stainless steel, aluminum, "INCONEL," "HAYNES," and "HASTALLOY," and are typically used for loading and positioning substrates into the chamber, for chamber walls, and for controlling process gas flow into and out of the chamber. Ceramic components such as quartz guards and high temperature components are generally used to contain the corrosive process gases or plasma in the chamber. The components in the process chamber often corrode in corrosive process gas, particularly in reactive halogen gases and plasmas thereof. For example, a plasma of nitrogen trifluoride (which is used to clean process chambers), contains reactive fluorine species that readily corrode metal components.
Corrosion of the components within the process chamber by the corrosive process environment limits the life of the processing apparatus, thereby increasing the down time of the apparatus and substrate processing cost. Also, corroded components can flake off and form contaminant particles which can deposit on the substrate. It is difficult to non-destructively detect such contamination during the initial stages of processing the wafer. Thus, it is only in the final stages of the manufacturing process, when the fully processed semiconductor wafers are worth between $50,000 to $100,000 each, that the contaminant deposits are discovered, and the entire wafer is rejected.
Thus, there is a need for a corrosion resistant apparatus and processing components that resist corrosion when exposed to corrosive process environments, and which form reduced amounts of contaminant particles resulting from corrosion.